An apparatus includes a pixel array in which pixels for outputting an analog signal are arranged in a matrix, vertical output lines each of which is connected to pixels in a same column, A/D conversion units, which are individually connected to the vertical output lines, for converting the analog signal into a digital signal, and a constant current supply unit for supplying a constant current to the A/D conversion units. Each of the A/D conversion units includes an integration unit for integrating the constant current, a comparison unit for comparing the integrated constant current with the analog signal and outputting a comparison signal, and a digital signal storage unit for storing a digital signal corresponding to the comparison signal. The integration unit includes an input capacitor for receiving the constant current. The comparison unit is connected to the constant current supply unit via the input capacitor.
Legal claims defining the scope of protection, as filed with the USPTO.
1. An apparatus comprising: a pixel array in which a plurality of pixels for outputting an analog signal are arranged in a matrix; a plurality of vertical output lines each of which is connected to corresponding ones of the plurality of pixels in a same column of the pixel array; a plurality of A/D conversion units, which are individually connected to the plurality of vertical output lines, configured to convert the analog signal into a digital signal; and a constant current supply unit configured to supply a constant current to the plurality of A/D conversion units, and wherein each of the plurality of A/D conversion units includes, an integration unit configured to integrate the constant current, a comparison unit configured to compare the integrated constant current with the analog signal and output a comparison signal, and a digital signal storage unit configured to store a digital signal corresponding to the comparison signal, wherein the integration unit includes an input capacitor configured to receive the constant current from one terminal thereof, wherein the comparison unit is connected to the constant current supply unit via the input capacitor, wherein the constant current supply unit is provided for each A/D conversion unit group composed of corresponding ones of the plurality of A/D conversion units, wherein a Bayer color filter is provided for the plurality of pixels included in the pixel array, and wherein the A/D conversion unit group is provided for corresponding ones of the plurality of pixels on which color filters of the same color are individually placed.
2. The apparatus according to claim 1 , wherein the integration unit includes a differential amplifier having an inverting input terminal connected to the other terminal of the input capacitor.
3. The apparatus according to claim 2 , wherein the integration unit further includes a feedback capacitor configured to connect the inverting input terminal and an output terminal of the differential amplifier to each other.
4. The apparatus according to claim 3 , wherein one terminal of the input capacitor is connected to the constant current supply unit or corresponding one of the plurality of vertical output lines.
5. The apparatus according to claim 1 , further comprising a voltage supply unit configured to supply a fixed voltage to one terminal of the input capacitor via a reference signal supply line, and wherein the integration unit starts an integration operation for integrating the constant current after the voltage supply unit sets a voltage of one terminal of the input capacitor to the fixed voltage, and wherein a period from a time at which the integration operation is started to a time at which each of the plurality of A/D conversion units starts an A/D conversion operation is a period that is equal to or less than ten times of a time constant of the reference signal supply line.
6. An apparatus comprising: a pixel array in which a plurality of pixels for outputting an analog signal are arranged in a matrix; a plurality of vertical output lines each of which is connected to corresponding ones of the plurality of pixels in a same column of the pixel array; a plurality of A/D conversion units, which are individually connected to the plurality of vertical output lines, configured to convert the analog signal into a digital signal; a constant current supply unit configured to supply a constant current to the plurality of A/D conversion units; and a switch unit configured to selectively connect a vertical output line from the plurality of vertical output lines and the constant current supply unit to an input terminal of an A/D conversion unit of the plurality of A/D conversion units, and wherein each of the plurality of A/D conversion units includes an integration unit and a comparison unit, wherein the integration unit includes an input capacitor having one terminal connected to the switch unit and the other terminal connected to an inverting input terminal of a differential amplifier, wherein the constant current supply unit is provided for each A/D conversion unit group composed of corresponding ones of the plurality of A/D conversion units, wherein a Bayer color filter is provided for the plurality of pixels included in the pixel array, and wherein the A/D conversion unit group is provided for corresponding ones of the plurality of pixels on which color filters of the same color are individually placed.
7. The apparatus according to claim 6 , wherein the integration unit further includes a feedback capacitor disposed between the inverting input terminal and an output terminal of the differential amplifier.
8. The apparatus according to claim 7 , wherein the comparison unit is connected to an output terminal of the integration unit via a connection capacitor.
9. A system comprising: the apparatus according to claim 1 ; an optical system configured to form an image onto the pixel array; and a signal processing unit configured to process a signal output from the apparatus.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
October 28, 2009
April 16, 2013
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